The genetic and environmental determinants of noninsulin dependent diabetes mellitus and the natural history of its vascular complications are being studied in an Amerindian community. The study also includes other diseases common in the study population, such as cataract, cholelithiasis, several types of arthritis, and adverse outcomes of pregnancy. The project provided evidence for genetic determinants of diabetes on two chromosomes and for both intrauterine and postnatal environmental risk factors for diabetes. Insulin resistance and/or huperinsulinemia appear to be important initial abnormalities in the development of diabetes. Eye examinations and retinal photography are used in the study of risk factors for diabetic retinopathy and other eye diseases such as cataract.